The invention relates to a feeding apparatus for melting furnaces for the continuous melting of scrap, preferably for the melting of prepared light metal scrap material.
Feeding arrangements for melting furnaces, especially for pit, cupola, or blast furnaces became known in a number of constructional variations.
For example a pit furnace used in the melting of aluminum scrap became known (aluminum handbook). The feeding of the scrap is performed here through a bricked-up pit, which serves at the same as the melting space and comprises as a lower limit a tilted melting bridge. The pit furnace has in series connected therewith one or two collecting troughs. The collecting troughs will become heated by special burners, the waste gas of which will flow into the pit furnace.
The disadvantages of such known construction reside in that the chute cone for the scrap material cannot be regulated, and that the light scrap, such as sheet metal and especially lacquered and oiled, contaminated scrap material will become oxidized, as a result of the direct application of the burning flame, and the organic adhesions will become decomposed through the high temperatures of the flame and will split-off oxygen. As a result, a high metal loss takes place. In connection with light material scrap there will be a completely unmeltable slick mountain present, the removal of which will present difficulties.
A method became known furthermore for the melting of light metal chips and especially thin waste material (German Pat. No. 820,968). The chips are dried and pre-formed in a revolving tubular furnace heated by the waste gases of an open hearth furnace and are fed thereafter through a shaft into the metal smelting area of an open hearth furnace. The feeding of the raw material is performed outside of the furnace area and insulated from the flame gases. The waste gases are used for the pre-warming and the drying of the material to be melted in a separate rotating tubular furnace or kiln. This means that in addition to the melting furnace an additional rotating kiln is necessary, coupled with an increased space requirement and requires also a larger mechanical layout for the operation.
Furthermore, there is also known a device for the feeding of the filling material and the removal of the reaction gases from a closed electrical melting furnace (DE-OS 2,830,720). It is characterized in that a pipe conduit system serves for the supplying of the filling material from a main pipe and which leads directly into the trough of the furnace through the center part of the arched roof thereof, and is determined by the mass of the material to be fed and it is disposed in equal distances from the associated electrodes and comprises also auxiliary piping, which are arranged near each electrode diametrically with respect to the central pipe and with respect to the axis of such electrode.
Inasmuch as in this solution the chute cone is placed onto the melting bath and, thereby, the material comes in direct contact with the arc, the use of such supply arrangement within a plasma furnace would lead to a disadvantage in that a high oxidation of the material to be melted would take place through the direct application of the plasma arc to it.
Furthermore, such supply arrangement will require a very high structural layout.